Justice Oliver Wendell Holmes pioneered the clear and present danger test as the constitutional yardstick for determining when the government could punish speech that might cause social harms. The Supreme Court’s decision in Schenck v. United States, with Justice Holmes writing for a unanimous bench, was issued on March 3, 1919. Schenck held that the government may criminalize speech if it has a bad tendency–meaning that it makes unlawful conduct more likely to take place.
By the fall of 1919, however, Justice Holmes had experienced a serious change of heart. Although nominally continuing to advocate for the use of the clear and present danger test to determine when the government may criminalize mere speech, Holmes’s articulation of the test underwent a radical transformation between March 3 and November 10. During this period, the clear and present danger test, at least as Justice Holmes articulated and applied it, underwent a near-total transformation from a very weak test that permitted the government to proscribe speech that could have a bad tendency to a highly demanding test that required the government to tolerate even speech “fraught with death” in order to meet the requirements of the First Amendment.
Ronald J. Krotoszynski, Jr., The Clear and Present Dangers of the Clear and Present Danger Test: Schenck and Abrams Revisited, 72 SMU L. Rev. 415 (2019).